What if pants could make me a better runner? With a half-marathon ahead of me, I decided it was time to try compression tights for training. As I struggled to pull a pair onto my slightly overweight legs, I could feel the skintight fabric transforming them from slack to firm, without any flexing. I stood up and marveled at how sleek and aerodynamic I looked. You could bounce a quarter off my thigh. Before I'd run a single step, my muscles seemed focused on the work I planned to do.

Enough people believed these claims to make sales of compression gear jump 170 percent from 2008 to 2010, giving it a 5 percent share of the sports apparel market, according to a recent consumer-research report. Customers are willing to pay a premium for the squeeze; according to the same report, retail margins for compression gear are 46 percent, compared to 43 percent for regular athletic clothing.

And it's true that compression gear isn't an ordinary pair of spandex pants. Made with tighter elastic to better hold its shape, compression apparel also delivers graduated pressure, meaning garments are tighter around the ankle than the knee, which helps improve circulation from the lower leg.

Whatever the compression did for my self-image, though, it didn't make me run faster. Researchers from Australia to Indiana have been studying whether compression apparel delivers its purported benefits. I kept track of my own running times, with and without tights, and that data led me to the same conclusion as the scientists: If you're looking for better endurance or more speed, don't bother with compression gear. It makes no difference.

Earlier studies had showed that runners, cyclists and other athletes experienced improved blood flow through their muscles when wearing compression gear during workouts in the lab. It seems logical to extrapolate that greater blood flow means better oxygenation of muscles, and thus improved performance.

Somewhere along that supposed chain of causation, however, things stopped linking up. Improving blood flow to muscles isn't exactly junk science on the level of Power Balance wristbands or Phiten necklaces. Before becoming a fad in sports apparel, compression garmets were used to treat patients suffering from poor circulation, by applying pressure that improves blood flow in the veins.

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For instance, my grandmother, a smoker for nearly seven decades, began suffering from such poor circulation a few years back that she could no longer walk. After a few days of wearing doctor-prescribed compression stockings, she was back on her feet, shuffling around again.

But if you're not a senior citizen, and your athletic goals are higher than simply becoming ambulatory, compression gear isn't going to make you more mobile. In my own exercise routine, I wanted to see if I could run faster and for a longer time. So I alternated wearing and not wearing my 2XU socks or tights on runs of varying distances. Admittedly, there were countless variables that entered into each workout, but I tried to go at the same time of day, with the same pre-run food, tracking my time and distance with a GPS watch.

In a study published last year in the Journal of Sports Physiology and Performance, researchers in Australia did a similar test, but with decidedly more scientific rigor. They put 11 middle-distance runners on treadmills to see how long they could run at 90 percent of their VO2max (a gauge of how much oxygen the body can take up, which reveals aerobic capacity) before tapping out. For each trial they measured time to exhaustion, blood lactate levels, heart rate, expired gas, and muscle oxygenation with a sensor placed on the thigh.

Neither those test subjects nor I could run farther distances or at a higher speed with the tights. The Aussie researchers observed through all their monitoring only "limited physiological changes." And while the tights improved blood flow in the legs, possibly promoting clearance of metabolic waste, the scientists called the effect trivial for athletes : "any improvement in the clearance of waste products is insufficient to negate the development of fatigue."

So much for endurance. But compression apparel manufacturers also claim it will increase muscle power. Basketball players would love the ability to run down the court faster and jump higher when finishing at the rim. Maybe that's why the likes of Dwyane Wade and Kobe Bryant don the gear.

To see if this was true, researchers at Indiana University put 25 athletes in three types of compression shorts: one that fit properly according to manufacturer specs, one that was a little tighter than that, and one that was looser than the specs. The researchers looked for the benefit of compression by testing the athletes' vertical jumps, because the biomechanics of jumping mimic other anaerobic activities. They didn't find one.

And neither did I. I wasn't running faster and I wasn't running farther. But I did notice one very helpful benefit—I felt better the day after a long run in compression tights.

That mattered, because training isn't just about one run on a given day. To log enough miles each week, I have to do long runs on back-to-back days, especially over the weekend. On Saturday, I'll go for 10 to 12 miles and follow up on Sunday with five to six more. When I wore compression on a Saturday, I felt less muscle soreness and fatigue when I ran on Sunday. That ability to bounce back made for a more effective training run.

But I worried that this could just be a placebo effect. Did I feel better merely because I had convinced myself that my tights had done the trick? Researchers in New Zealand found a way to control for that. In a study published in the February issue of the Journal of Strength and Conditioning Research and broken down on Runner's World's Sweat Science blog, cyclists rode 40-kilometer time trials, then did the time trials again the next day.

During the 24 hours between rides, the cyclists were given tights to wear, but they weren't told that some were wearing basic spandex tights and the others compression. A week later, they did the trial again, except this time those who had worn spandex the week before got compression tights and vice versa. On the second-day rides, cyclists went 1.2 percent faster when they wore compressing gear during recovery as opposed to spandex.

What's the underlying biological mechanism that allowed for greater recovery? The researchers weren't sure, but speculated that increased blood flow helped restock the muscles with their fuel, glycogen. In the Aussie study above, the scientists speculated that compression could aid recovery by helping to clear metabolic waste. Whatever was at work, I certainly felt better.

Was that improvement in recovery worth the $55 or more that a lot of these compression socks and tights will set you back? It depends on your level and frequency of activity. If you're a runner or an athlete who depends on recovery in order to train the next day, there's benefit to buying them.

But if you're a weekend warrior who plays pick-up basketball or rec-league soccer every once in a while? You can pass. The benefits you'd be buying compression gear for—to run faster or jump higher—don't exist.